Chain-stitch sewing machine



19:67 A. LANZENDORFER 06 CHAIN- STITCH SEWING MACHINE Filed Feb. .20, 1964 4 Sheets-Sheet l I l 5 4 fl 12 (1 \l. 9

\ ANTON LANZENDURFEP q V INVENTOR.

Jan. 31, 1967 A. LANZENDORFER CHAIN-STITCH SEWING MACHINE 4 Sheets-Sheet 2 Filed Feb. .20, 1964 ANTON LANZENDGRFEP INVENTORL Jan. 31, 1967 A. LANZENDGRFER 3,301,206

CHAIN-STITCH SEWING MACHINE Filed Feb. .20, 1964 V 4 Sheets-Sheet s ANTON LANZENDORFER INVENTOR.

AGENE 1967 A. LANZENDORFER 3,301, 03

CHAIN-STITCH SEWING MACHINE Filed Feb. .20, 1964 4 Sheets-Sheet 4 [HIHIII ANTON LANZENDOPFER I NVENTOR.

AGENT United States Patent 3,301,206 CHAIN-STITCH SEWING MACHINE Anton Lanzendiirfer, Bieleteld, Germany, assignor to Durkoppwerke Aktiengesellschaft, Bielefelrl, Germany, a corporation of Germany Filed Feb. 20, 1964, Ser. No. 346.188 Claims priority, application Germany, Feb. 21, 1963,

4 ,951 4 Claims. (Cl. 112-199) My present invention relates to chain-stitch sewing machines and, more particularly, to machines for stitching a succession of simple chain stitches or for so-called single-chain stitching.

Sewing machines for single-chain stitching have been provided heretofore with hook-like members adapted to describe an elliptical path below the stitch plate and around the needle position for engagement of a thread in order to hold it in position during a subsequent pass of the needle. The member was thus adapted to provide the so-called thread triangle constituting the lower portion of each chain stitch. The mechanism hitherto used for this purpose was, for the most part, highly complex with a plurality of moving thread-gripping parts whose synchronism was difficult to attain and was readily disrupted. Moreover, in these earlier systems, the thread triangle had its apex directly below the material to be stitched with the base of the triangle close to the point of the needle. This arrangement frequently permitted the needle to pass outside the triangle and resulted in dropped stitches or interruption of the chain especially when heavy material was to be 'stitched. The disadvantages of these earlier systems were particularly evident when the chain stitch was required over relatively sharp curves and corners or different lengths of stitching were to be produced. In these cases the movement of the triangle with the material to be stitched in a curved path or at a sharp angle to the previous stitching resulted in a removal of the triangle from the path of the needle and an interruption in the chain stitching.

It is the principal object of the present invention, therefore, to provide an improved chain-stitch sewing machine of the character described.

A further object of this invention is to provide a chainstitch sewing machine wherein the thread triangle below the stitch plate can be established repeatedly with as- 3,301,265 Patented Jan. 31, 1967 ice loop to be engaged thereby and distended between this 7 element and the hook-shaped member to receive the The stationary element is provided with a finger whose tip is receivable within the arcuate groove during the latter part of each cycle of the movement of the hook-shaped member to ensure distention of the loop carried by the latter between this finger and an edge of the member.

According to a more specific feature of this invention, the hook-shaped member is provided with a recess whose flanks are spaced apart in the direction of movement of the member and constitute first and second edges engageable with the thread loop and forming therewith a lostmotion connection. Thus the first edge can be a forward fiank of the hook-shaped member and extends generally transversely to the direction of movement of the member for initial engagement with a thread loop during withdrawal of the needle through the stitch plate, this edge carrying the loop beyond the stationary finger. The other flank of the recess constitutes a second edge, also extending transversely to the direction of movement of the member, engageable with the loop upon its movement into engagement with the stationary finger, both edges lying below the latter. The tip of the finger can be relatively ball-shaped and of small diameter so as to extend with play into the groove and not to interfere with the movement of the hook-shaped member although co-open ating therewith to retain temporarily a portion of the thread loop for distention thereof at least until the movement of the hook-shaped member withdraws the finger from the groove.

surance even when the direction of stitching is changed sharply.

These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing, in a chain-stitch sewing machine, loop-forming means adjacent and below the stitch plate for releasably maintaining a thread loop adapted to clear the needle upon passage thereof through the plate, this loop-forming means including a movable member and a stationary element as will be described in greater detail hereinafter. An essential feature of the present invention resides in the provision of a hook-shaped member swingably displaceable about a substantially horizontal pivotal axis generally parallel to the stitch plate and to a succession of stitches produced by the needle for engagement with the thread loop formed by the latter upon its withdrawal through the plate, the hook-shaped member being provided with a lateral face perpendicular to this pivotal axis and formed with an arcuate groove preferably centered thereon; the stationary element is disposed adjacent the generally elliptical path of the hook-shaped member around the needle in such manner that the hookshaped member initially passes the element remote therefrom to carry the thread loop beyond this element and subsequently approaches the element so as to permit the It is clear, therefore, that this co-operative relationship of the hook-shaped member and the finger, resulting from the shifting of the hook-shaped member in the directio-n of the minor axis of its elliptical path, is independent of the position of the apex of the previous chain stitch and thus ensures the maintenance of a loop adapted to receive the needle in spite of any previous motion of the fabric or material which has been stitched.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a partial side-elevational view of a chainstitch sewing machine with parts broken away, illustrating only a portion of the machine;

FIG. 2 is an elevational view, partly broken away, taken at right angles to the view of FIG. 1;

FIG. 3 is a fragmentary bottom-plan view of the Sta tionary finger;

FIGS. 48 are perspective views respectively illustrating, somewhat diagrammatically, successive steps in the operation of the device; and

FIG. 9 is a diagrammatic elevational view of a mechanism suitable for operating the loop-forming means of the present invention.

In FIG. 1 I show the essential parts of a chain-stitch sewing machine which, in a conventional manner, is formed with a support plate or base 1 and an arm or head 2 in which the needle 3 is generally vertically recip roca-ble by a conventional cam and drive mechanism diagrammatically illustrated in FIG. 9. The usual" presser foot 3' is also provided for holding a sheet material against the stitch plate 5 which is apertured to permit the tooth portion 6 of the conventional feed device 6 to pass therethrou-gh. The feed device moves, in the usual manner, in a somewhat elliptical path in a vertical plane.

Below the stitch plate 5, there is provided a hoo-k shapped gripper member 4 of the loop-forming means which further includes a stationary element 7 whose finger 7' is disposed adjacent the path of the hook-shaped member 4 and is provided with a tip 8 (FIGS. 2 and 3) so disposed along the path of member 4 that, during the rearward swinging movement of the latter, tip 8 is received in an arcuate groove 9 formed in the lateral face 4' of the member 4. The finger element 7 -is mounted on the underside of the support plate 1 by fastening screws 10 which are received within bores 11 (FIG. 1) with sufficient play to permit the horizontal adjustment of the element 7 relatively to the generally elliptical path of the gripper member 4; the element 7 is provided with a bar 13 for mounting as will be apparent from FIGS. 2 and 3. In order to permit the vertical adjustment of the tip 8 of finger 7 to accommodate this tip to the height of gripper member 4 (ie. its distance below the stitch plate the fastening bar 13 can be cantilevered on the support plate 1 and can be somewhat resilient so that an adjusting screw 12, bearing against the underside of the support plate 1, can move the tip 8 vertically. A locking nut 12 is provided to prevent undesirable loosening of the screw during operation. When screw 12 is threaded further into the bar 13, the tip 8 is moved downwardly within the width of the groove 9 and vice versa.

The gripper member 4 is further provided with a recess 14 (FIG. 4) along its underside whose flanks form the edges 15 and 1-6 which constitute a lost-motion linkage with a thread loop engaged thereby. Edge 15 constitutes the aforementioned second edge of the present invention and isproximal to the point of the hook-like member or plate 4 and serves to maintain the thread loop for a predetermined period during the advance of the needle in order to ensure penetration of the needle in the loop. Edge 1 6 is disposed adjacent the case of the gripper member 4 and serves to displace the thread loop beyond the stationary finger 7.

The operation of the device is as follows:

When the sewing needle. 3 (FIG. 4), at the conclusion of the formation of a. previous stitch S, commences its upstroke upon reaching its lower dead-point position, it forms a loop L (FIG. 5) into which the gripper member 4, in the beginning of its elliptical movement, passes. The gripper member (FIG. 5 and 6) moves through this loop L and engages it with its edge 16 in such manner that the loop is displaced beyond the element 7 during the forward motion of the gripper member when the latter is remote from the finger 7. As the forward motion of the gripper member 4 continues, a portion 9' of the groove 9 beyond the edge 16 is brought close to the finger 7 until the tip 8 extends into this groove whereupon the rearward movement of the gripper member commences. This reaward movement can be substantially linear with respect to the finger 7 and results in an engagement of the loop L by edge 15 While part of the loop is held by finger 7. The distended triangle 17 thus resulting receives the needle 3 (FIG. 7) which had previously begun its downstroke to release thread during the loop-forming stage (FIG. 6). When the tip 8 is fully withdrawn from the groove 9, the needle 3 has been received within the loop and the gripper member 4 withdraws therefrom (FIG. 8) to again commence a stitch-forming stroke while the needle 3 concludes the formation of the new chain stitch S.

In FIGS. 2 and 9 I show the mechanism 34 for controlling the elliptical movement of the hook-shaped gripper member 4. The latter is mounted upon the arm 18 in which it is removably held by a locking screw 19, this arm 18 being removably mounted upon a shaft 20 by a clamping screw 21. Shaft 20 is axially shiftable in housing 22 and is provided with a sleeve 23 keyed thereto and formed with a cam groove 24 in which a pin 25 of the housing is slidable. A pair of compression springs 26, 27 bear against the sleeve 23 and center of the shaft 20 with respect to the pin 25 while a pittnan 28 is mounted upon the splined end 29 of the shaft. A cran k 30 and a transmission lever 31 apply an angular oscillation to the shaft 20 when driven by a bevel gear 32 which is coupled to the needle drive 33 (indicated diagrammatically). Upon angular displacement of the shaft 20 by the assembly 28-32, cam groove 24 advances and retracts the shaft axially during its counterclockwise and clockwise movements, respectively, as seen from the right-hand end of the shaft. The generally elliptical movement previously described is thus applied to the gripper member 4.

The invention as described and illustrated is believed to admit many modifications and variations wit-hinthe ability of persons skilled in the art, all such modifications and variations being deemed to be included within the spirit and scope of the appended claims.

What is claimed is:

1. In chain-stitch sewing machine, in combination:

a sewing-machine stitch plate;

a head provided with a needle reciprocably displaceable on said head generally transversely to said plate for forming a succession of chain stitches;

and loop-forming means adjacent said plate for releasably maintaining a thread loop adapted to clear said needle upon passage thereof through said plate, said loop-forming means including a generally hookshaped member swingably displaceable about a pivotal axis generally parallel to said plate and said succession of stitches and transverse to said needle for engagement with a thread loop formed by said needle upon withdrawal thereof through said plate, said member having a face perpendicular to said pivotal axis formed with an arcuate groove,

mechanism for imparting to said member a generally elliptical motion around said needle with the major axis of the elliptical motion substantially transverse to said pivotal axis, and

a stationary element disposed adjacent the path of said member and having a finger received in said groove upon movement of said member toward said ele ment, said element being engageable with a thread loop entrained by said member for distending said loop to receive said needle upon a subsequent passage thereof through said plate.

2. In a chain-stitch sewing machine, in combination:

a sewitg-machine stitch plate;

a head provided with a needle reciprocably displaceable on said head generally transversely to said plate for forming a succession of chain stitches;

and loop-forming means adjacent said plate for releasably maintaining a thread loop adapted to clear said needle upon passage thereof through said plate, said loop-forming means including a generally hook shaped member swingably displac-eable about a pivota1 axis generally parallel to said plate and said suc ccession of stitches and transverse to said needle for engagement with a thread loop formed by said needle upon withdrawal thereof through said plate said member 'being formed with an elongated groove transverse to the thread of the loop,

mechanism for imparting to said member a generally elliptical motion around said needle with the major axis of the elliptical motion substantially transverse to said pivotal axis, and

an element disposed adjacent the path of said member and periodically received in said groove while being engageable with a thread loop entrained by said member for distending said loop to receive said needle upon a subsequent passage thereof through said plate, said member being provided with a first edge extending generally transversely of the direction of movement of said member for engagement with a thread loop over a portion of said path distal from said element and a second edge extending generally transversely of said member for engagement with the loop for opening said loop against said element;

3. In a chain-stitch sewing machine, in combination:

a sewing-machine stitch plate;

a head provided with a needle reciprocably displaceable on said head generally transversely to said plate for forming a succession of chain stitches;

and loop-forming means adjacent said plate for releasably maintaining a thread loop adapted to clear said needle upon passage thereof through said plate, said loop-forming means including a generally hookshaped member swingably displacea'ble about a pivotal axis generally parallel to said plate and said succession of stitches and transverse to said needle for engagement with a thread loop formed by said needle upon withdrawal thereof through said plate, said member having a face perpendicular to said pivotal axis formed with an arcuate groove,

mechanism for imparting to said member a generally elliptical motion around said needle with the major axis of the elliptical motion substantially transverse to said pivotal axis,

a stationary element disposed adjacent the path of said member and having a finger received in said groove upon movement of said member toward said element, said element being engageable with a thread loop entrained by said member for distending said loop to receive said needle upon a subsequent passage thereof through said plate, said member being provided with a first edge extending generally transversely of the direction of movement of said member for engagement with a thread loop over a portion of said path distal from said element and a second edge extending generally transversely of said member for engagement with the loop upon said finger projecting into said groove for opening said loop against said element.

4. In a chain-stitch sewing machine, in combination:

support means;

a generally horizontal sewing-machine stitch plate on said support means;

a head on said support means provided With a needle generally vertically reciproca'bly displacea'ble on said head through said plate for forming a succession of chain stitches thereupon;

drive means on said head for reciprocating said needle;

and loop-forming means below said plate for releasably maintaining a thread loop adapted to clear said needle upon passage thereof through said plate, said loopforming means including a generally hook-shaped member swingably displaceable about a substantially horizontal pivotal axis generally parallel to said plate and said succession of stitches and transverse to said needle for engagement with a thread loop formed by said needle upon withdrawal thereof through said plate, said member having a face perpendicular to said pivotal axis formed with an arcuate groove,

mechanism synchronized With said drive means for imparting to said member a generally elliptical motion around said needle with the major axis of the elliptical motion substantially transverse to said pivotal axis,

a stationary element disposed adjacent the path of aid member and having a finger received in said groove upon movement of said member toward said element, said element being engageable with a thread loop entrained by said member for distending said loop to receive said needle upon a subsequent passage thereof through said plate, said member being provided with a first edge extending generally transversely of the direction of movement of said member for engagement with a thread loop over a portion of said path distal from said element and a second edge extending generally transversely of said member for engagement with the loop upon said finger projecting into said groove for opening said loop against said element, and

adjusting means on said support for vertically displacing said element selectively to accommodate said finger to said groove.

References Cited by the Examiner UNITED STATES PATENTS JORDAN FRANKLIN, Primary Examiner. 

1. IN A CHAIN-STITCH SEWING MACHINE, IN COMBINATION: A SEWING-MACHINE STITCH PLATE; A HEAD PROVIDED WITH A NEEDLE RECIPROCABLY DISPLACEABLE ON SAID HEAD GENERALLY TRANSVERSELY TO SAID PLATE FOR FORMING A SUCCESSION OF CHAIN STITCHES; AND LOOP-FORMING MEANS ADJACENT SAID PLATE FOR RELEASABLY MAINTAINING A THREAD LOOP ADAPTED TO CLEAR SAID NEEDLE UPON PASSAGE THEREOF THROUGH SAID PLATE, SAID LOOP-FORMING MEANS INCLUDING A GENERALLY HOOKSHAPED MEMBER SWINGABLY DISPLACEABLE ABOUT A PIVOTAL AXIS GENERALLY PARALLEL TO SAID PLATE AND SAID SUCCESSION OF STITCHES AND TRANSVERSE TO SAID NEEDLE FOR ENGAGEMENT WITH A THREAD LOOP FORMED BY SAID NEEDLE UPON WITHDRAWAL THEREOF THROUGH SAID PLATE, SAID MEMBER HAVING A FACE PERPENDICULAR TO SAID PIVOTAL AXIS FORMED WITH AN ARCUATE GROOVE, MECHANISM FOR IMPARTING TO SAID MEMBER A GENERALLY ELLIPTICAL MOTION AROUND SAID NEEDLE WITH THE MAJOR AXIS OF THE ELLIPTICAL MOTION SUBSTANTIALLY TRANSVERSE TO SAID PIVOTAL AXIS, AND A STATIONARY ELEMENT DISPOSED ADJACENT THE PATH OF SAID MEMBER AND HAVING A FINGER RECEIVED IN SAID GROOVE UPON MOVEMENT OF SAID MEMBER TOWARD SAID ELEMENT, SAID ELEMENT BEING ENGAGEABLE WITH A THREAD LOOP ENTRAINED BY SAID MEMBER FOR DISTENDING SAID LOOP TO RECEIVE SAID NEEDLE UPON A SUBSEQUENT PASSAGE THEREOF THROUGH SAID PLATE. 